. >> the tallest in the united states. >> tallest building in the united states. that's right. even taller than the building, still sears tower in chicago. i know you know chicago. >> hancock building. >> there you go. >> we can call it the sears. >> the willis. >> what you talking about, willis. >> used to be the second largest, the hancock, the willis. call it sears tower. >> let's just move on. there is no sign of a breakthrough in chicago. teachers strike, enters day three at 350,000 students remaining out of the classroom. the union president says they're miles apart from reaching any agreements. more from abc's alex perez. >> reporter: union teachers holding strong at the picket line in chicago, refusing to back down. >> we did not start this fight. >> reporter: the fight is about a program that would eventually base as much as 40% of a teacher's evaluation on standardized test scores. a formula that union argues will unfairly cost teachers their jobs. the mayor believes the new measure will help turn around the district's staggering statistics. >> it is about ensuring ov